56 IOWA ACADEMY OF SCIENCES. 



the middle ledges in the Pine creek conglomerate. It is seen 

 to contain three rounded boulders from eight inches to one 

 foot in diameter. One of these consists of gneiss, one of mica 

 schist and one of quartzite. In a collection of 100 pebbles from 

 this ledge, different rocks were represented by the number of 

 pebbles indicated in the following list: 



Greenstone 26 per cent 



White quartz 26 " " 



Yellow chert 18 '' " 



Granite (mostly red) 7 " " 



Light red orthoclase 5 " " 



Coal measure rock 4 " " 



Black felsite 3 " " 



Quartz-biotite schist 3 " " 



Faintly pinkish white quartz 2 " " 



Quartz speckled with jasper 2 " " 



Red quartzite 1 " " 



Hornblende rock 1 " " 



Milky quartz 1 " " 



Gneiss 1 " " 



The author is inclined to the opinion that this conglomerate 

 in Muscatine and that exposed on Pine creek are both outliers 

 of the same formation, but he has no suggestion to offer as to 

 what age they really belong farther than as above stated. 



FOREST TREES OF ADAIR COUNTY, IOWA. 



BY JAMES E. GOW. 



In order to understand the forestry conditions of Adair 

 county, a short description of the lay of the land and the 

 nature of the soil is first necessary. The county lies along the 

 crest of the " grand divide," between the Mississippi and the 

 Missouri, so that a line drawn along the crest of the ridge 

 traverses it diagonally from northwest to southeast. The land 

 is undulating enough to secure an easy natural drainage, but 

 not so undulating as to be difficult of cultivation, except in a 

 few isolated localities. The soil is a rich, black loam, varying 

 in thickness from a few inches to ten or fifteen feet and under- 

 lain by a stiff, yellow clay. Here and there, the larger streams 

 may be found flowing over beds of limestone, but as a rule 



